I don't think anyone, even Cameron, doubts that if the Rangers trade Yu and rebuild for 2016 that there will be a dip in attendance. But we're still talking 25,000+ coming out every game -- not Minute-Maid-Graveyard type #'s.
But Cameron also probably recognizes that a Texas Rangers rebuild and the Houston Astros rebuild are two completely different things. Houston had a barren farm and gutted payroll to the point where it was basically a minor league team playing. Texas is positioned enough with their young talent and current contracts to still be a competitive team in 2015 even with a rebuild. They are essentially trying to rebuild to championship caliber while still being a team that can be at the very least competitive.
Add to that a Texas rebuild is a 1 year type thing. Accept 2015 won't be that great and build for 2016. The Astros rebuild was essentially "We've been mediocre for 5 years, we're going to suck for the next 4, and then we'll be good". That's a tough pill for fans to swallow.
I'm very bearish on 2015 Rangers, but that's as a contender. I still think worst-case scenario whether Texas "goes for it" or "sells off" is 75+ wins.